Abstract
Initiation of DNA replication in eukaryotes is dependent on the activity of protein phosphatase 2A (PP2A), but specific phosphoprotein substrates pertinent to this requirement have not been identified. A novel regulatory subunit of PP2A, termed PR48, was identified by a yeast two-hybrid screen of a human placental cDNA library, using human Cdc6, an essential component of prereplicative complexes, as bait. PR48 binds specifically to an amino-terminal segment of Cdc6 and forms functional holoenzyme complexes with A and C subunits of PP2A. PR48 localizes to the nucleus of mammalian cells, and its forced overexpression perturbs cell cycle progression, causing a G(1) arrest. These results suggest that dephosphorylation of Cdc6 by PP2A, mediated by a specific interaction with PR48, is a regulatory event controlling initiation of DNA replication in mammalian cells.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Cell Cycle Proteins / metabolism*
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Cell Line
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Cloning, Molecular
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DNA Replication*
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Female
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Gene Library
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HeLa Cells
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Humans
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Macromolecular Substances
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Mice
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Molecular Sequence Data
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Phosphoprotein Phosphatases / chemistry
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Phosphoprotein Phosphatases / genetics
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Phosphoprotein Phosphatases / metabolism*
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Phylogeny
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Placenta / enzymology
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Pregnancy
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Protein Phosphatase 2
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Protein Structure, Quaternary
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Rabbits
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae Proteins*
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Sequence Alignment
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Sequence Homology, Amino Acid
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Spodoptera
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Transfection
Substances
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CDC6 protein, S cerevisiae
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Cell Cycle Proteins
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Macromolecular Substances
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PPP2R3B protein, human
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Phosphoprotein Phosphatases
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Protein Phosphatase 2